Customisation of Javascript Drop Down menu

We are having difficulties in implementing a javascript based drop down menu system on our website. It did work fine originally though with the odd glitch in Firefox but nothing major, but now despite not modifying it, it does not work at all in Firefox, or in Google Chrome. The menu is a basic drop down menu called chromemenu, freely available on various websites. The menu allows for customisation with css. We have been designing a website template and it works fine in Internet Explorer (latest edition) but not in other browser. We have recently changed our server and wonder if this has anything to do with it. We need some one to figure out what is causing this problem. It still works fine on another site on which it is implemented so I have no idea why it is not working now on this new site. Thanks Andy